diff --git a/src/com/android/browser/BrowserProvider.java b/src/com/android/browser/BrowserProvider.java
index bf1f9d5..a6ceb8b 100644
--- a/src/com/android/browser/BrowserProvider.java
+++ b/src/com/android/browser/BrowserProvider.java
@@ -159,7 +159,8 @@
     // 20 -> 21 Added touch_icon
     // 21 -> 22 Remove "clientid"
     // 22 -> 23 Added user_entered
-    private static final int DATABASE_VERSION = 23;
+    // 23 -> 24 Url not allowed to be null anymore.
+    private static final int DATABASE_VERSION = 24;
 
     // Regular expression which matches http://, followed by some stuff, followed by
     // optionally a trailing slash, all matched as separate groups.
@@ -239,7 +240,7 @@
             db.execSQL("CREATE TABLE bookmarks (" +
                     "_id INTEGER PRIMARY KEY," +
                     "title TEXT," +
-                    "url TEXT," +
+                    "url TEXT NOT NULL," +
                     "visits INTEGER," +
                     "date LONG," +
                     "created LONG," +
@@ -291,6 +292,27 @@
             }
             if (oldVersion < 23) {
                 db.execSQL("ALTER TABLE bookmarks ADD COLUMN user_entered INTEGER;");
+            }
+            if (oldVersion < 24) {
+                /* SQLite does not support ALTER COLUMN, hence the lengthy code. */
+                db.execSQL("DELETE FROM bookmarks WHERE url IS NULL;");
+                db.execSQL("ALTER TABLE bookmarks RENAME TO bookmarks_temp;");
+                db.execSQL("CREATE TABLE bookmarks (" +
+                        "_id INTEGER PRIMARY KEY," +
+                        "title TEXT," +
+                        "url TEXT NOT NULL," +
+                        "visits INTEGER," +
+                        "date LONG," +
+                        "created LONG," +
+                        "description TEXT," +
+                        "bookmark INTEGER," +
+                        "favicon BLOB DEFAULT NULL," +
+                        "thumbnail BLOB DEFAULT NULL," +
+                        "touch_icon BLOB DEFAULT NULL," +
+                        "user_entered INTEGER" +
+                        ");");
+                db.execSQL("INSERT INTO bookmarks SELECT * FROM bookmarks_temp;");
+                db.execSQL("DROP TABLE bookmarks_temp;");
             } else {
                 db.execSQL("DROP TABLE IF EXISTS bookmarks");
                 db.execSQL("DROP TABLE IF EXISTS searches");